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It's hard to take April statistics seriously, given the sample sizes involved. We've seen far more Aprils begin with players doing unexpectedly well (or surprisingly poor) compared to expectations, and while their overall season stats might end up better for it, they don't keep up their hot start over the course of the year. April starts tend to be a timing thing, with players performing in ways they might in the middle of the season, but since these are the only numbers we have to go on, things look that much more impressive (or depressing) at this early stage.
That's why it's hard to get too excited about the strikeout rate of Clay Buchholz. The Red Sox hurler is punching out over a batter per inning in what would easily be a career-high for him, and it's led to what would also be a career-best strikeout-to-walk ratio. The thing that needs to be pointed out is that he's pitched just five games, and thrown just 37-2/3 innings -- that's only about one-sixth of the season out of the way for Buchholz.
With that being said, though, it's worth noting that research has been done for this specific thing: determining when you can begin to trust the data of a season, and in the case of Buchholz, strikeout rate specifically. Russell Carleton, who worked for Baseball Prospectus and then the Cleveland Indians and is back with BP once more, researched this last decade for a now-defunct statistics blog called Statistically Speaking. His findings (now cataloged at FanGraphs' sabermetrics library) showed that you can begin to treat strikeout rates -- considered by strikeout per plate appearance in his research -- as stabilized after 150 batters faced.
Buchholz has faced an AL-leading 144 hitters through his first five starts. It's not quite 150, but it's pretty close, and, barring injury or catastrophe, he'll pass it within the first inning or two of his next start that'll come early next week. Coming into 2013, Buchholz had struck out 6.7 batters per nine innings, and 17.4 percent of the hitters he faced. In 2013, he's at 9.3 punch outs per nine, and 27 percent of the batters he's faced -- that's an extraordinary jump, to the point of being somewhat unbelievable. There's evidence in history to suggest something like this can occur, though:
NAME | Year 1 | Year 2 | SO | PA | SO | PA | Year 1% | Year 2% |
Alan Benes | 1996 | 1997 | 131 | 840 | 160 | 666 | 15.6 | 24.0 |
Pedro Martinez | 1998 | 1999 | 251 | 951 | 313 | 835 | 26.4 | 37.5 |
Ron Villone | 2000 | 2001 | 77 | 643 | 113 | 523 | 12.0 | 21.6 |
Curt Schilling | 2000 | 2001 | 168 | 862 | 293 | 1021 | 19.5 | 28.7 |
Esteban Loaiza | 2002 | 2003 | 87 | 670 | 207 | 922 | 13.0 | 22.5 |
Ben Sheets | 2003 | 2004 | 157 | 931 | 264 | 937 | 16.9 | 28.2 |
Daniel Cabrera | 2004 | 2005 | 76 | 662 | 157 | 716 | 11.5 | 21.9 |
Brett Myers | 2004 | 2005 | 116 | 778 | 208 | 905 | 14.9 | 23.0 |
Erik Bedard | 2006 | 2007 | 171 | 844 | 221 | 733 | 20.3 | 30.2 |
Jorge De La Rosa | 2007 | 2008 | 82 | 589 | 128 | 571 | 13.9 | 22.4 |
Jon Lester | 2008 | 2009 | 152 | 874 | 225 | 843 | 17.4 | 26.7 |
Justin Verlander | 2008 | 2009 | 163 | 880 | 269 | 982 | 18.5 | 27.4 |
Zack Greinke | 2010 | 2011 | 181 | 919 | 201 | 715 | 19.7 | 28.1 |
Jason Hammel | 2011 | 2012 | 94 | 739 | 113 | 493 | 12.7 | 22.9 |
R.A. Dickey | 2011 | 2012 | 134 | 876 | 230 | 927 | 15.3 | 24.8 |
Carlos Villanueva | 2011 | 2012 | 68 | 454 | 122 | 521 | 15.0 | 23.4 |
Max Scherzer | 2011 | 2012 | 174 | 832 | 231 | 787 | 20.9 | 29.4 |
Since 1993, 17 pitchers -- including Boston's own Jon Lester -- have seen their K/PA increase by at least eight percentage points from one year to the next, minimum 100 innings in each season. The quality of these pitchers themselves varies, but that's not the key question with Buchholz: what's important is that jumps in strikeout rate like the one he is currently experiencing do happen, even if they seem unbelievable at first glance.
Consider that, plus the fact that it's been expected Buchholz would eventually evolve as a starter once he grew into his stuff -- that whole fractured spine thing kind of interrupted his growth as a pitcher, though. From Baseball Prospectus 2011 (which released before the 2011 season began), courtesy of the same author you're reading right now:
Pitchers can have fantastic stuff without racking up strikeouts, and Buchholz is exhibit A. The young right-hander should punch out more batters with his mid-90s heater, a 90-mph slider, and his finest pitch, a vanishing change-up, and those strikeouts are coming. His fastballs and sliders were fouled off at a 20-percent clip, which suggests that once he grows into his stuff, the whiffs will pile up. Normally, it would be odd to talk about a 26-year-old growing into anything but his thirties, but the velocity is new to Buccholz, whose slider averaged 81 mph two years ago. The added giddyup resulted from a change to his grip, which now resembles that used for a cutter, and the slider now functions as a fastball variant with a break he can command. Even without the extra strikeouts, the 25-year-old induced weak contact and grounders aplenty. Buchholz may never post a 2.33 ERA again, but he does have ace potential.
Are we finally seeing him growing into his stuff, as suggested a few years ago after he led the American League in ERA and finished sixth in the Cy Young vote? He's nearly at the minimum threshold for his strikeout rate to stabilize, recent history says the kind of jump he's experiencing can occur -- even if it's not particularly common -- and he certainly has the stuff in his deep, five-pitch repertoire to miss bats consistently if he applies himself in that fashion. It appears he finally is utilizing his stuff in a consistent and effective way that allows him to induce contact when needed and miss bats when that's preferable, and with that development should come that ace potential the Red Sox and their fans have long waited for.
Thanks to Baseball Prospectus' Rob McQuown for data research